Chemical Heat Mass Transfer Multiple Choice Questions - Set 33 - ObjectiveBooks
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# Practice Test: Question Set - 33

1. For specified tube outside diameter, higher BWG means higher
(A) Tube thickness
(B) Cross-sectional area
(C) Weight per unit length
(D) None of these

2. 1 BTU/hr.ft.°F is equal to __________ kcal/hr. m.°C.
(A) 1.49
(B) 1
(C) 4.88
(D) None of these

3. A long iron rod initially at a temperature of 20°C has one end dipped in boiling water (100°C) at time, t = 0. The curved surface of the rod is insulated so that heat conduction is one dimensional in the axial direction. The temperature at a distance 100 mm from the dipped end becomes 40°C at time, t = 200 s. The same temperature is achieved at a distance of 200 mm from the dipped end at time
(A) t = 283 s
(B) t = 356 s
(C) t = 400 s
(D) t = 800 s

4. Multiple effect evaporation is generally recommended, when the
(A) Large scale evaporation of liquor is needed
(B) Corrosive liquids are to be concentrated
(C) Fuel is cheaply available
(D) Evaporation on small scale is to be done

5. Value of Prandtl number for water ranges from
(A) 1 to 2
(B) 5 to 10
(C) 100 to 500
(D) 1000 to 2000

6. Which of the following is correct?
(A) Rate = Driving force × Resistance
(B) Driving force = Rate × Resistance
(C) Resistance = Driving force × Rate
(D) Rate = Resistance/Driving force

7. For a fluid flowing in an annulus space, the wetted perimeter for heat transfer and pressure drop are
(A) Same
(B) Different
(C) Never different
(D) Linearly related

8. Steam is routed through the tube in case of a __________ evaporator.
(B) Horizontal tube
(C) Short tube vertical
(D) Long tube vertical

9. 1000 kg of wet solids are to be dried from 60% to 20% moisture (by weight). The mass of moisture removed in kg is
(A) 520
(B) 200
(C) 400
(D) 500

10. The sum of reflectivity and absorptivity for an opaque body is equal to
(A) 0.5
(B) 1
(C) 0
(D) 2

11. Dropwise condensation occurs on __________ surfaces.
(A) Clean and dirt free
(B) Smooth clean
(C) Contaminated cooling
(D) Polished

12. In a backward feed multiple effect evaporator
(A) Feed is introduced in the first effect
(B) Feed flows from low pressure to high pressure
(C) No pumps are required between successive effects
(D) None of these

13. Conduction occurs in the buffer zone for a fluid flowing through a heated pipe, only when Prandtl number is
(A) 0.1
(B) > 1
(C) < 1
(D) 1

14. For a given ambient air temperature with increase in the thickness of insulation of a hot cylindrical pipe, the rate of heat loss from the surface would
(A) Decrease
(B) Increase
(C) First decrease and then increase
(D) First increase and then decrease

15. In thermal radiation for a black body (where, ε is emissivity and α is absorptivity)
(A) α = 1; ε ≠ 1
(B) α ≠ 1, ε = 1
(C) α ≠ 1, ε ≠ 1
(D) α = 1; ε = 1

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